Base structure for high temperature furnace



y 1958 E. PUGH 2,834,590

BASE STRUCTURE FOR HIGH TEMPERATURE FURNACE Original Filed Jan. 8, 1954 /,v wswzm 5. Push United rates BASE STRUCTURE FOR HIGH TEMPERATURE FURNACE Emerson Pugh, Downers Grove, IlL, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Original application January 8, 1954, Serial No. 403,001,

now Patent No. 2,798,716, dated July 9, 1957. Divided and this application May 17, 1957, Serial No. 659,863

3 Claims. (Cl. 263-49) rapidly and the hearth structure has to be replaced frequently.

An object of the invention is to provide a furnace having an improved base structure with a hearth capable of withstanding a relatively high temperature.-

Another object of the invention is to provide a quickly replaceable unitary health structure for a furnace, which may be readily moved into operative position or quickly removed therefrom.

A furnace illustrating certain features of the invention may have a stationary platform mounted on the floor for supporting a plate thereon in spaced relation to the floor. The plate has a marginal 'portion supporting a domed hood of the furnace to form a gas-tight chamber for heating articles therein. A hearth is supported removably on the plate and comprises a metal plate having a layer of refractory material thereon and provided with a plurality of vertical holes for receiving the upper end portions of tubes extending through and attached fixedly to the first plate for conducting gases into and out of the heating chamber, and a tray is mounted on top of the hearth for supporting the articles to be heated. The hearth protects the first plate and the stationary platform from the intense heat in the heating chamber and when the hearth becomes worn out it may readily be raised over the ends of the tubes and removed from the first plate and another new hearth quickly substituted therefor.

Other objects and advantages of the invention will become apparent by reference to the following detailed description and the accompanying drawings illustrating a preferred embodiment thereof, in which:

Fig. 1 is a fragmentary vertical central sectional view through a high temperature furnace showing the removable hearth therein;

Fig. 2 is a fragmentary plan view of the removable hearth; and

Fig. 3 is a vertical sectional view of the removable hearth taken on line 3-3 of Fig. 2.

Referring to the drawings the high temperature furnace comprises generally a base 10, a domed metal hood 12 adapted to be lowered onto the base to form an inner heating chamber 14 in Which the articles to be heated are placed, and an inverted cup-shaped bell 16 adapted to fit over and enclose the hood 12 and be supported on the lower portion thereof to form an outer chamber 17 enclosing the inner heating chamber 14. A plurality of electrical heating elements 18 are mounted on the inner atent 2,834,590 Patented May 13, 1958 ice exhausting the atmosphere from the heatingchamber. An

additional pipe 28 extends through the base and the hearth to provide an opening for the insertion of a thermocouple or other measuring instruments into the inner chamber of the furnace.

The base comprises a platform 30, a base plate 31 supported thereon, and a hearth 32 removably supported on the plate 31. The platform 30 has a heavy horizontally disposed plate 33 with a plurality of depending legs 34 resting on a floor 35 for supporting the furnace in spaced relation to the floor. Clearance apertures are formed in the platform 30 for the pipes 21, 25, 28 which are welded to the base plate 31 and project upwardly through the removable hearth 32. The base plate 31 has a depending skirt 36 which has an annular laterally extending channel-shaped shelf portion 37 with a sealing gasket 38 therein. The hood 12 is supported on the shelf portion 37 of the base plate 31 with the lower edge of the hood 12 resting on the sealing gasket and cooperating therewith to provide the sealed inner heating chamber 14.

An annular laterally disposed channel-shaped shelf portion 40 adjacent the lower edge of the hood has a sealing gasket 41 therein cooperable with a Water cooled sealing ring 44 on the lower end of the bell 16 and for supporting the bell and forming the sealed outer chamber 17.

The removable hearth 32 comprises a metal circular plate 45 on which is laid a plurality of courses of fire brick or other refractory material to form a heat insulating slab 46 of predetermined thickness. The side of the hearth 32 or the slab 46 is conical to conform to an intermediate conical wall portion 48 of the hood 12, and clearance apertures 49 are formed in the hearth for the pipes 21, 25, and 28. If desired, the plate 45 of the removable hearth may be reinforced with angle bars 50. The articles to be heat treated may be placed upon the upper surface of the slab 46 of the hearth but preferably are placed upon a grid or a perforated metal tray 51 provided with feet 52 which rest on the upper surface of the slab.

With the articles placed on the tray 51 the hood 12 and the bell 16 are lowered into assembled position on the base to form the sealed inner chamber 14 and outer chamber 17, the atmosphere is then purged from the chambers and the appropriate gases flowed thereinto, after which the heating elements are energized to heat the inner chamber to a predetermined temperature to heat treat the parts. The arrangement of the hood 12 and the base 10 of the furnace is such that the relatively thick slab 46 of the hearth serves to form a bottom for the gas tight inner heating chamber 14 and to insulate the supporting plate 45 of the hearth, the base plate 31, and the metal plate 33 of the platform 30 from the intense heat of the heating chamber 14 which rises to a temperature of from 2000 to 2200" F. so that the closure plate 31 during the operation of the furnace is maintained at a relatively low temperature of from 200 to 300 F. With this design of furnace only the slab 46 of refractory material is exposed to high temperatures while the base plate 31 is relatively cool and free from oxidation. Thus, the hearth structure does not deteriorate rapidly with use but has a relatively long life.

When the refractory slab 46 deteriorates through repeated heating and cooling stresses to the point where it has to be replaced, it is a relatively simple matter, after the bell 16 and the hood 12 have been removed, to raise the hearth 32 from the closure plate 31 and the platform 30 to a level above the ends of the pipes 21, 25, and 28 and remove it, and then place another prefabricated hearth 32 on the plate 31. The removal of an old hearth and the replacement thereof with a new hearth requires about half an hour and thus it does not necessitate an extended shut down of the furnace and does not appreciably interfere with the continued opera tion thereof.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of this invention. Numerous other arrange ments may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. A base for a high temperature furnace having a removable domed hood, which comprises a stationary platform supported on a floor, a metal base plate supported on the stationary platform above and in spaced relation to the floor and having a marginal portion for supporting the domed hood to form a gas-tight chamber for heating articles therein, a unitary hearth structure supported removably on the base plate comprising a metal hearth plate supported on the base plate, a layer of refractory material supported upon the hearth plate, said layer of refractory material forming a bottom for the gas-tight chamber for insulating the hearth plate, the base plate, and the platform from direct exposure to heat within the chamber, and vertical tubes extending through and attached to the base plate with upper portions of said tubes extending through the hearth to the top surface thereof and with lower portions of said tubes extending through a portion of the platform and being detachably arranged to conduct gases into and out of said chamber, the hearth and the platform having clearance apertures for receiving the said tubes therein.

2. A base for a high temperature furnace having a removable domed hood, which comprises a metal base plate having a marginal portion for supporting the domed hood to form a gas-tight chamber for heating articles therein, a platform supported on a floor for supporting the base plate in spaced relation to the floor; a unitary hearth structure supported removably on the base plate comprising a metal hearth plate supported on the base plate, a layer of refractory material supported upon the hearth plate, said layer of refractory material forming a bottom for the gas-tight chamber to insulate the hearth plate, the base plate and the platform from direct exposure to heat within the chamber, vertical tubes extending through and attached to the base plate with upper portions of said tubes extending through the removable hearth to the top surface thereof and lower portions of said tubes depending from the base plate through a portion of the platform and being connectible to pipelines for conducting gases into and out of said chamber, and an article supporting tray mounted upon the upper surface of the layer of refractory material.

3. A base for a high temperature furnace having a removable domed hood, which comprises a stationary platform having a horizontal supporting member and a plurality of depending legs in engagement with a floor, a metal base plate supported on the horizontal supporting member of the platform above and in spaced relation to the floor and having a marginal portion for supporting the domed hood to form a gas-tight chamber for heating articles therein, a unitary hearth structure supported removably on the base plate comprising a metal hearth plate supported on the base plate, a layer of refractory material supported upon the hearth plate, said layer of refractory material forming a bottom for the gas-tight chamber to insulate the hearth plate, the base plate and the platform from direct exposure to heat within the chamber, vertical tubes extending through and attached to the base plate with upper portions of said tubes extending through the hearth to the top surface thereof and lower portions of said tubes depending below the supporting member of the platform and being detachably connectible to conduits to conduct gases into and out of said chamber, the hearth and the platform having clearance openings for receiving the said tubes therein, and an article supporting tray mounted upon the upper surface of the layer of refractory material.

No references cited. 

